Geomagnetic Storms:Probabilities for significant disturbances in Earth's magnetic field are given for three activity levels: active, minor storm, severe storm

Updated at: 2012 Sep 20 2200 UTC

Mid-latitudes

0-24 hr

24-48 hr

ACTIVE

30 %

30 %

MINOR

05 %

05 %

SEVERE

01 %

01 %

High latitudes

0-24 hr

24-48 hr

ACTIVE

35 %

35 %

MINOR

10 %

10 %

SEVERE

01 %

01 %

Thursday, Sep. 20, 2012

What's up in space

Hang the Transit of Venus on your wall! Hubble-quality images from NASA's Solar Dynamics Observatory are now available as metallic posters in the Space Weather Store.

CMEs MISS EARTH: The Solar and Heliospheric Observatory (SOHO) has observed at least three CMEs billowing away from the sun during the last 24 hours. However, none of the clouds are heading for Earth. The source of the explosions appears to be on the far side of the sun. Aurora alerts:text, voice.

AUTUMN LIGHTS: Northern autumn is only two days away--and that means it's aurora season. For reasons researchers don't fully understand, the days around equinoxes are the best times to see Northern Lights. Indeed, the Arctic Circle is glowing. Last night, Ole C. Salomonsen photographed the ongoing display from Tromsø, Norway:

"The sky was full of awesome auroras in magnifcent shapes and colors," says Salomonsen. "I also saw a magnificent blue fireball streaking through the lights above my favorite mountain Otertinden. It was the biggest fireball I have ever caught on camera. What a great photographic moment for me!"

More scenes like this are in the offing. NOAA forecasters estimate a 25% to 30% chance of strong polar geomagnetic storms for the next three nights as a series of solar wind streams gently buffet Earth's magnetic field. Aurora alerts:text, voice.

DISAPPEARING ASTEROID: More than a week after amateur astronomers witnessed an explosion in the cloudtops of Jupiter more powerful than an atomic bomb, no debris has appeared at the blast site. "I took a picture of Jupiter on Sept. 15th using the same telescope that I used to observe the brilliant fireball flash above Jupiter's clouds on the morning of Sept. 10th," reports Dan Petersen of Racine, Wisconsin, the man who saw the explosion first. "This photo shows that five days after the explosion there was still no signature debris cloud near 'ground zero.'"

The absense of debris suggests that the source of the explosion, probably an asteroid, was small. Studies show that Jupiter is a frequent target for 10-meter class space rock, and this is almost certainly another example of Jupiter getting hit. The giant planet absorbed the explosion and swallowed the remains of the asteroid whole.

Potentially Hazardous Asteroids (PHAs) are space rocks larger than approximately 100m that can come closer to Earth than 0.05 AU. None of the known PHAs is on a collision course with our planet, although astronomers are finding new ones all the time.